Service function guideFuse and Relay Testing

This guide covers the complete diagnostic process for automotive fuses and relays, from understanding the power distribution system to tracing repeat failures that keep blowing fuses or burning relay contacts. It is written for working mechanics and serious DIYers who already know how to use a multimeter and a test light, and who want a repeatable, professional method rather than guesswork. You will learn how to prepare safely, perform voltage-drop and resistance tests on fuses and relays, verify results, and adapt the procedure across different vehicle architectures. By the end, you will be able to diagnose a blown fuse or faulty relay with confidence and trace the root cause of repeat failures without replacing parts blindly.